The invention relates generally to electrical circuit breakers and, more particularly, to the tripping of circuit breakers.
Circuit breakers for high voltage applications (e.g. 27 kV) typically include a mechanical tripping device, which is in turn activated by an external trip unit. A typical modern trip unit is an electronic device which senses a variety of fault conditions, including overcurrent, and for example activates a spring-loaded magnetically latched actuator connected to the circuit breaker trip device. Typical prior art devices require a manual reset after a circuit breaker has been tripped.
Also relevant in the context of the invention is an “LD series” circuit breaker module, described hereinbelow in greater detail, manufactured by Tavrida Electric. A typical installation of a Tavrida Electric breaker includes an electronic control module which generates current pulses applied to a magnetic actuator within the circuit breaker module to provide close and open (trip) functionality. A drawback of the Tavrida breaker is that the electronic control module requires control power in order to generate a current pulse to trip the circuit breaker. Control power is not always conveniently available. Moreover, control power may not be available sufficiently quickly when power is restored following a power interruption, which could become an issue in the event their is a fault downstream of the circuit breaker.